# Medical Dosage Calculations

As a pharmacy tech student, you may be wondering why you'd need to learn medical dosage calculations. Most directly, you'll be using them in many IV mixture and other dosage questions.

However, there are actually several other reasons, and patient safety is at the top of the list. In the field, you may be asked to determine a pediatric dosage. But, equally important, you may be able to recognize an oversight or error and save someone from an unnecessary overdose. So, let's look at some of the most often used formulas:

Young's Rule:

Pediatric formula based on Age. This one is valid for a patients under the age of 12. In children who are within average body weight for their, Young's and Clark's rule formulas are usually very close. When you're taking the PTCBor even just a practice quiz, if you're given only an age and asked to calculate a pediatric dosage, default to Young's rule.

Clark's Rule:

Pediatric formula based on weight (in Lbs.), this formula is valid for patients weighing less than 150 pounds. You'll need to be prepared to see it on the Pharmacy Tech Test.  Luckily, the names are easy to distinguish, since Young's rule uses age, and the name even implies it. While taking the PTCBor a practice quiz, if you're given only a weight and asked to calculate a pediatric dosage, default to Clark's rule.

Body Surface Area:

This formula is Based on Height and weight (in Lbs.), and used in applications that require pinpoint accuracy. It's commonly used to dose cancer patients to achieve optimal treatment and prevent chemotherapy under-dosing / over-dosing.

Dosage by Weight:

This is something you're going to see often in IV Mixture questions. It's quite basic and you just plug in and multiply numbers. The toughest math for pharm tech students is IV flow rate, and this is usually the first step.

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